1. Field of the Invention
The following relates to water heating devices, and more particularly to a water heater having (i) at least two sensors, each of which are operable to provide an output signal indicative of a water temperature, and (ii) sensor diagnostics for determining a health status of the water heater.
2. Description of Related Art
Water heaters are used in homes, businesses and just about any establishment having the need to heat water. Water heaters heat water using the simple “heat rises” principle. In operation, water heaters heat cold or ambient temperature water entering at or near the bottom of the water heater to a desired temperature using a gas-fired burner, an electric heater or some other form of energy.
During a heating cycle, the cold or ambient temperature water at the bottom of the water heater becomes hotter and begins to rise towards the top of the water heater. Denser water, once on top of the water being heated, falls toward the bottom of the water heater so that it can be heated to the desired temperature. After the temperature of the water at the bottom of the water heater reaches a certain desired temperature, the water heater stops heating the water.
When demand for hot water arises (e.g., someone turns on a faucet to run a shower) fresh, cold or ambient water enters the water heater and “pushes out” or supplies the hotter water at or near the top of the water heater. When a sufficient amount of the hotter water exits from the top of the water heater so that the fresh, cold or ambient water entering the bottom causes the temperature of the water at the bottom of the tank to drop below the desired temperature, the water heater repeats the heat cycling. Alternatively, a heat cycle may occur as a result of the water heater standing idle for an extended period of time.
A conventional water heater typically has at least one heating element or “heater,” such as a gas-fired and/or electric burner. To take advantage of the “heat-rises” principle, the heater is located at or near the bottom of the water heater. Each water heater typically also has at least one thermostat or controller for controlling the heater.
To facilitate the heating of water, the controller receives signals related to the temperature of the water. When these signals indicate that the water temperature is below a predetermined threshold, for example, when the water temperature is below 120 degrees Fahrenheit, the controller turns on the heater and the water at or near the bottom of the water heater begins to heat.
After some time, the temperature of the water at the bottom of the water heater increases to a second threshold, which, for example, may be about 140 degrees Fahrenheit. When receiving signals indicating that the water temperature at the bottom of the tank is greater than the second threshold, the controller causes the heater to reduce its heat output or, alternatively, causes the heater to turn off. The heat cycle begins again when the temperature of the water at the bottom of the water heater drops below the first threshold.
Unfortunately, the controller, under certain conditions, may fail to receive reliable, repeatable, reproducible, and/or accurate or acceptable signals corresponding to the temperatures of the water in the water tank 102. These errant signals can affect the efficient operation and possibly the safety of the water heater. Thus, it is desirable to provide a method and system to detect errant signals, correct the errors, and/or terminate the operation of the water heater in an effort to make the water heater more reliable, repeatable, reproducible, and/or accurate.